--- /dev/null
+https://bugs.gentoo.org/705730
+
+gcc-10 enabled f-no-common by default. Broke syslinux linking.
+--- a/mk/com32.mk
++++ b/mk/com32.mk
+@@ -47,6 +47,7 @@ GCCOPT += $(call gcc_ok,-falign-functions=0,-malign-functions=0)
+ GCCOPT += $(call gcc_ok,-falign-jumps=0,-malign-jumps=0)
+ GCCOPT += $(call gcc_ok,-falign-labels=0,-malign-labels=0)
+ GCCOPT += $(call gcc_ok,-falign-loops=0,-malign-loops=0)
++GCCOPT += $(call gcc_ok,-fcommon)
+
+ ifeq ($(FWCLASS),EFI)
+ GCCOPT += -mno-red-zone
+--- a/mk/elf.mk
++++ b/mk/elf.mk
+@@ -42,6 +42,7 @@ GCCOPT += $(call gcc_ok,-falign-functions=0,-malign-functions=0)
+ GCCOPT += $(call gcc_ok,-falign-jumps=0,-malign-jumps=0)
+ GCCOPT += $(call gcc_ok,-falign-labels=0,-malign-labels=0)
+ GCCOPT += $(call gcc_ok,-falign-loops=0,-malign-loops=0)
++GCCOPT += $(call gcc_ok,-fcommon)
+
+ com32 = $(topdir)/com32
+ core = $(topdir)/core
+--- a/mk/embedded.mk
++++ b/mk/embedded.mk
+@@ -51,6 +51,7 @@ GCCOPT += $(call gcc_ok,-falign-jumps=0,-malign-jumps=0)
+ GCCOPT += $(call gcc_ok,-falign-labels=0,-malign-labels=0)
+ GCCOPT += $(call gcc_ok,-falign-loops=0,-malign-loops=0)
+ GCCOPT += $(call gcc_ok,-fvisibility=hidden)
++GCCOPT += $(call gcc_ok,-fcommon)
+
+ LIBGCC := $(shell $(CC) $(GCCOPT) --print-libgcc)
+
+--- a/mk/lib.mk
++++ b/mk/lib.mk
+@@ -28,6 +28,7 @@ GCCOPT += $(call gcc_ok,-falign-functions=0,-malign-functions=0)
+ GCCOPT += $(call gcc_ok,-falign-jumps=0,-malign-jumps=0)
+ GCCOPT += $(call gcc_ok,-falign-labels=0,-malign-labels=0)
+ GCCOPT += $(call gcc_ok,-falign-loops=0,-malign-loops=0)
++GCCOPT += $(call gcc_ok,-fcommon)
+
+ INCLUDE = -I$(SRC)
+ STRIP = strip --strip-all -R .comment -R .note
+--- a/mk/efi.mk
++++ b/mk/efi.mk
+@@ -7,7 +7,7 @@ core = $(topdir)/core
+ # Set up architecture specifics; for cross compilation, set ARCH as apt
+ # gnuefi sets up architecture specifics in ia32 or x86_64 sub directories
+ # set up the LIBDIR and EFIINC for building for the appropriate architecture
+-GCCOPT := $(call gcc_ok,-fno-stack-protector,)
++GCCOPT := $(call gcc_ok,-fno-stack-protector,) $(call gcc_ok,-fcommon)
+ EFIINC = $(objdir)/include/efi
+ LIBDIR = $(objdir)/lib
+
--- /dev/null
+diff --git a/dos/string.h b/dos/string.h
+index f648de2d..407d0233 100644
+--- a/dos/string.h
++++ b/dos/string.h
+@@ -5,12 +5,22 @@
+ #ifndef _STRING_H
+ #define _STRING_H
+
++#include <stddef.h>
++
+ /* Standard routines */
+ #define memcpy(a,b,c) __builtin_memcpy(a,b,c)
+ #define memmove(a,b,c) __builtin_memmove(a,b,c)
+ #define memset(a,b,c) __builtin_memset(a,b,c)
+ #define strcpy(a,b) __builtin_strcpy(a,b)
+-#define strlen(a) __builtin_strlen(a)
++#define strlen(a) inline_strlen(a)
++
++/* replacement for builtin strlen that appears to get optimized away */
++static inline size_t inline_strlen(const char *str)
++{
++ size_t l;
++ for (l = 0; *str++; l++);
++ return l;
++}
+
+ /* This only returns true or false */
+ static inline int memcmp(const void *__m1, const void *__m2, unsigned int __n)